The correct tire pressure in the pneumatic tires of a motor vehicle is of great significance in several aspects. Accordingly, an air pressure in the tires which is too low, for example, leads to an increased rolling resistance and to an increase in the consumption of fuel by the motor vehicle and, furthermore, to an increased wear of the tires. In the worst case, when the air pressure in a tire of the motor vehicle has dropped so greatly, this can even lead to the situation wherein the tire becomes greatly overheated because of the increased rolling resistance and blows out. Accidents which are caused by tire blowouts mostly have serious consequences so that they are to be avoided if at all possible. An air pressure in the tires of the motor vehicle which is too great is also viewed as disadvantageous. This leads to the situation that the tires are no longer in contact with the roadway with their entire road contact surface but only with a portion of the roadway contact surface. This has the consequence of increased wear of the tires and a deterioration of the driving safety.
For the reasons advanced above, modern motor vehicles often have a tire pressure control arrangement which monitors the air pressure in the tires and outputs a signal when the air pressure in at least one of the tires of the motor vehicle drops below a lower threshold value or exceeds an upper threshold value. The driver is then afforded the possibility to so control the air pressure that the air pressure again lies between the threshold values. In most tire pressure control arrangements, the threshold values are set independently of the weight of the vehicle or the laden state of the motor vehicle.
There are, however, tire pressure control arrangements wherein the threshold values can be inputted manually so that they can be adapted to the vehicle weight or laden state thereof. This is purposeful in that, for a high vehicle weight (that is, a high laden state of the motor vehicle), the lower and the upper threshold value are increased and, for a low vehicle weight (that is, for a low laden state), these threshold values are lowered in order to consider the laden state. The safety of the motor vehicle can be increased by tire pressure control arrangements wherein a manual input of the threshold values is possible because the laden state of the motor vehicle is considered when there is a warning from the tire pressure control arrangement to the driver. Often, however, the adaptation of the threshold values is overlooked by the driver for various reasons so that the theoretically conceivable gain in safety is defeated.